U.S. patent number 8,023,959 [Application Number 11/427,262] was granted by the patent office on 2011-09-20 for method and system for personal area networks.
This patent grant is currently assigned to Motorola Mobility, Inc.. Invention is credited to Mahesh B. Bhuta, Eric T. Eaton, Jorge L. Perdomo.
United States Patent |
8,023,959 |
Bhuta , et al. |
September 20, 2011 |
Method and system for personal area networks
Abstract
A system (160) and method (400) is provided for validating a
location of a tracking device. The method can include monitoring
(902) a set of signal strengths (600) to one or more personal area
networks (104) and one or more cellular towers (110), generating
(906) a Radio Frequency Time Profile RFTP (700) from the set of
signal strengths, comparing (908) the RFTP o coverage variation
limits (720) of one or more pre-calibrated paths, and signaling
(910) an alert if the set of signal strengths are not within the
coverage variation limit of the one or more pre-calibrated paths.
The RFTP is a time series of the signal strengths between the
tracking device and the one or more PANs resulting from a change in
location of the tracking device.
Inventors: |
Bhuta; Mahesh B. (Coral
Springs, FL), Eaton; Eric T. (Lake Worth, FL), Perdomo;
Jorge L. (Boca Raton, FL) |
Assignee: |
Motorola Mobility, Inc.
(Libertyville, IL)
|
Family
ID: |
38877351 |
Appl.
No.: |
11/427,262 |
Filed: |
June 28, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080004036 A1 |
Jan 3, 2008 |
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Current U.S.
Class: |
455/456.1;
455/456.2; 455/456.3; 455/456.6; 455/456.5 |
Current CPC
Class: |
G01S
19/48 (20130101); G01S 5/0252 (20130101); G01S
5/0263 (20130101); H04W 64/006 (20130101) |
Current International
Class: |
H04W
24/00 (20090101) |
Field of
Search: |
;455/456.1,456.2,456.3,456.5,456.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1441235 |
|
Jul 2004 |
|
EP |
|
1532465 |
|
May 2005 |
|
EP |
|
05012599 |
|
Jan 1993 |
|
JP |
|
05120599 |
|
May 1993 |
|
JP |
|
02204900 |
|
Aug 1999 |
|
JP |
|
2002111806 |
|
Apr 2002 |
|
JP |
|
200173466 |
|
Oct 2001 |
|
WO |
|
WO 2005060304 |
|
Jun 2005 |
|
WO |
|
Other References
www.airespace.com., "RF Fingerprinting: Enabling Accurate Location
Tracking for WLANs",
http://www.airespace.com/technology/technote.sub.--rf.sub.--fingerprintin-
g.php, 2 pages, website last visited Jun. 28, 2006. cited by other
.
Mobileguardian LLC, a wholly-owned subsidiary of Nemerex Corp.,
"MobileGuardian (TM) Sponsors Teen Driver Education Program",
Location Tracking and Stolen Vehicle Recovery Solution Can Assist
Parents in Monitoring Teen Drivers; Jul. 31, 2003; 2 pages,
ForRealease.com; website last visited Oct. 5, 2005. cited by other
.
Bahl, et al., "RADAR: An In-Building RF-based User Location and
Tracking System," IEEE 2000, vol. 2, pp. 775-784, Mar. 2000. cited
by other .
United States Patent and Trademark Office, "Non-Final Office Action
Summary", Nov. 30, 2007, pp. 1-12, U.S. Appl. No. 11/257,602. cited
by other.
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Primary Examiner: Negron; Daniell L
Assistant Examiner: Nguyen; Huy D
Claims
What is claimed is:
1. A tracking system for validating a location suitable for use
with location Positioning Systems, comprising: a tracking device
that generates a Radio Frequency Profile (RFTP); one or more
personal area network units (PANs) communicatively coupled to the
tracking device; and a processor operable to: receive GPS data
reporting an immediate location of the tracking device; project a
path of the tracking device based on a history of the RFTP; predict
a location of the tracking device along the path; determine whether
the location is within a region of a last received GPS reading;
raise an alert if the location is outside a coverage variation
limit of a pre-calibrated path; and wherein the RFTP is a signature
of communication patterns recorded between the tracking device, the
PAN, and, if present, one or more external communications systems,
and the tracking system validates a location of the tracking device
based on the RFTP.
2. The tracking system of claim 1, wherein the tracking system
monitors the RFTP for communication pattern transitions, and
signals an alert if the communication pattern transitions are
outside a coverage variation limit of a monitored location.
3. The tracking system of claim 1, wherein the tracking system
validates the immediate location reported by the GPS in view of the
path.
4. The tracking system of claim 3, wherein the tracking system
predicts the location of the tracking device along the path when
GPS data for reporting a location of the tracking device is
unavailable.
5. The tracking system of claim 3, wherein the tracking device
tracks and stores one or more network readings including GPS data,
cellular signals, RF signal strengths, and PAN coverage, for
creating the RFTP.
6. The tracking system of claim 5, wherein the tracking system
determines changes in a time and location sequence of the tracking
device from the network readings for characterizing a safe
zone.
7. The tracking system of claim 1, wherein the RFTP includes a
first set of signal strength indicators measured between the
tracking device and the one or more cellular towers, and a second
set of signal strength indicators measured between the tracking
device and the one or more PANs, wherein the tracking device
monitors a first variation in the first set of signal strength
indicators and a second variation in the second set of signal
strengths over a time window for determining whether the variations
are within a coverage variation limit of a monitored location.
8. The tracking system of claim 1, wherein the tracking system
updates the RFTP based on one or more false alarms.
9. The tracking system of claim 1, wherein the PAN includes a
positional detector for determining whether the PAN has moved from
a pre-specified location.
10. The tracking system of claim 1, wherein the tracking device and
the PAN communicate over a non-network assisted communication
protocol including at least one from the group comprising:
BlueTooth, ZigBee, IEEE 802.11, and two-way radio.
11. The tracking system of claim 1, wherein the tracking device
further comprises: a modem for acquiring a coverage pattern from
one or more cellular towers and at least one personal area network
unit; and a processor for determining whether a variation in the
coverage pattern is within a monitored location, wherein the
processor captures one or more RF signals from the modem,
determines a signal strength of the one or more RF signals, and
compares the coverage pattern with a coverage variation limit of a
monitored location.
12. The tracking system of claim 1, wherein the personal area
network unit further comprises: a first modem for establishing
communication with one or more cellular towers or other PANs; a
second modem for establishing non-network assisted communication
with the tracking device; and a monitoring unit for comparing the
RTFP with one or more communication patterns from the one or more
cellular towers or other PANs.
Description
FIELD OF THE INVENTION
The present invention relates to mobile communication devices and,
more particularly, to reliable network coverage for location
awareness.
BACKGROUND
The use of portable electronic devices and mobile communication
devices has increased dramatically in recent years. Mobile
communication devices are capable of distributing various forms of
media and can also distribute location based information. Mobile
communications devices can be equipped with Global Positioning
Systems (GPS) for identifying a location of the mobile
communication device, and, accordingly, a user of the mobile
communication device. The GPS allows a monitoring system to
determine a physical position of the user's location through GPS
readings. The GPS readings can provide a coordinate of the mobile
communication device. Services can be provided in accordance with
the location of the mobile device based on the GPS readings. Such
services include location aware services which provide custom
services based on a location of the user.
A mobile communication device equipped with GPS can also be used to
monitor activity, or ensure that a user stays within a certain
area. For example, location awareness can be deployed for
monitoring children, the elderly, or individuals under a
surveillance order. The mobile communication device can be attached
to the user to monitor their location and movement. On problem
faced with location based systems is to be able to accurately
determine the location of the individual when GPS coverage has been
compromised. The mobile communication device may at times lose
coverage with a GPS satellite. For example, the signals from the
mobile communication device may be blocked by physical structures
such as buildings or walls. Under these conditions, the location of
the mobile communication device is temporarily unavailable. During
these times, the location of the user is unknown and uncertain.
Moreover, malicious attempts can be made to trick or confuse the
GPS system to provide misleading location information. For example,
the mobile communication device can be tampered with to provide
false readings. Under this situation, a monitoring system will not
only provide inaccurate readings, but it will also be unaware that
the readings are misleading. Accordingly, a need therefore exists
for a location awareness monitoring system that can verify a
location of a mobile communication device and determine when the
system readings are misleading.
SUMMARY
Broadly stated, embodiments of the invention are directed to a
monitoring system for validating a location of a device. One
embodiment of the invention is a tracking system augmented with
Global Positioning Systems (GPS) for validating a location of the
device. The system can include a tracking device that generates a
Radio Frequency Time Profile (RTFP), one or more personal area
network units (PANs) communicatively coupled to the tracking
device, and one or more cellular towers operatively coupled to the
personal area network and the tracking device. The RFTP can be a
time signature of communication patterns recorded between the
tracking device, the PAN, and the one or more cellular towers that
is generated in response to changes in a location of the tracking
device when GPS coverage is unavailable. The tracking system can
validate a location of the tracking device based on the RFTP. For
example, the tracking system can monitor the RFTP for communication
pattern transitions, and signal an alert if the communication
pattern transitions are outside a coverage variation limit of a
monitored location.
Embodiments of the invention also concern a method for generating
an RFTP. The method can include tracking and storing GPS readings
received by a tracking device for identifying one or more locations
of the tracking device, capturing a first set of time-series
communication patterns between the tracking device and one or more
cellular towers, capturing a second set of time-series
communication patterns between the tracking device and one or more
Personal Area Networks (PANs), and generating a Radio Frequency
Time Profile (RTFP) from the first set of time-series communication
patterns and the second set of time-series communication
patterns.
Embodiments of the invention also concern a method for validating a
location of a tracking device in a personal area network (PAN). The
method can include monitoring a set of signal strengths to one or
more personal area networks (PANs), generating a Radio Frequency
Time Profile (RTFP) from the set of signal strengths, wherein the
signal strengths change over time, comparing the Radio Frequency
Time Profile to coverage variation limits of one or more
pre-calibrated paths, and signaling an alert if the set of signal
strengths are not within the coverage variation limit of the one or
more pre-calibrated path. The method can further include monitoring
a second set of signal strengths to one or more cellular towers and
generating the RTFP from the set of signal strengths to the one or
more PANs and the second set of signal strengths from the one or
more cellular towers. In one arrangement, an alert can be raised if
the PAN has moved from a first location to a second location.
If GPS coverage has been lost, a path of the tracking device can be
projected based on the RFTP and a last received GPS location. A
location of the tracking device can be predicted based on the path,
and the location of the tracking device can be validated within a
monitored location. If coverage has not been lost, the RFTP can be
updated based on a recent GPS location. An alert can be raised if
the path deviates outside a coverage variation limit of a
pre-calibrated path. If the alert is valid, the coverage variation
limit can be enforced, and if the alert is invalid, a coverage
variation limit can be extended for reducing a false alarm rate.
Moreover, the tracking device provides self-learning aspects that
can enhance the RFTP as alarm situations are found to be valid or
invalid. The self learning aspects can improve alerting decisions
by reducing a false rate of alarms based on a history of alarms in
view of the RFTP.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the system, which are believed to be novel, are set
forth with particularity in the appended claims. The embodiments
herein, can be understood by reference to the following
description, taken in conjunction with the accompanying drawings,
in the several figures of which like reference numerals identify
like elements, and in which:
FIG. 1 is a diagram of a tracking device within a mobile
communication environment;
FIG. 2 is a schematic of a tracking device in accordance with the
embodiments of the invention;
FIG. 3 is a schematic of a Personal Area Network (PAN) in
accordance with the embodiments of the invention;
FIG. 4 is a diagram presenting one or more coverage areas in
accordance with the embodiments of the invention;
FIG. 5 is a method for generating a RFTP in accordance with the
embodiments of the invention;
FIG. 6 is a plot of a time-series communication signal within a
coverage variation limit in accordance with the embodiments of the
invention;
FIG. 7 is a plot of a RFTP signal within coverage variation limits
in accordance with the embodiments of the invention;
FIG. 8 is a method for determining an authorized location in
accordance with the embodiments of the invention;
FIG. 9 is a method for validating a location of a tracking device
based on a signal strength in accordance with the embodiments of
the invention;
FIG. 10 is a diagram of a communication signal variation for one or
more cellular towers in accordance with the embodiments of the
invention;
FIG. 11 is a diagram of a communication signal variation for one or
more Personal Area Networks in accordance with the embodiments of
the invention; and
FIG. 12 is a method for creating pre-calibrated coverage variation
patterns in accordance with the embodiments of the invention.
DETAILED DESCRIPTION
While the specification concludes with claims defining the features
of the embodiments of the invention that are regarded as novel, it
is believed that the method, system, and other embodiments will be
better understood from a consideration of the following description
in conjunction with the drawing figures, in which like reference
numerals are carried forward.
As required, detailed embodiments of the present method and system
are disclosed herein. However, it is to be understood that the
disclosed embodiments are merely exemplary, which can be embodied
in various forms. Therefore, specific structural and functional
details disclosed herein are not to be interpreted as limiting, but
merely as a basis for the claims and as a representative basis for
teaching one skilled in the art to variously employ the embodiments
of the present invention in virtually any appropriately detailed
structure. Further, the terms and phrases used herein are not
intended to be limiting but rather to provide an understandable
description of the embodiment herein.
The terms "a" or "an," as used herein, are defined as one or more
than one. The term "plurality," as used herein, is defined as two
or more than two. The term "another," as used herein, is defined as
at least a second or more. The terms "including" and/or "having,"
as used herein, are defined as comprising (i.e., open language).
The term "processor" can be defined as any number of suitable
processors, controllers, units, or the like that carry out a
pre-programmed or programmed set of instructions.
The terms "program," "software application," and the like as used
herein, are defined as a sequence of instructions designed for
execution on a computer system. A program, computer program, or
software application may include a subroutine, a function, a
procedure, an object method, an object implementation, an
executable application, an applet, a servlet, a source code, an
object code, a shared library/dynamic load library and/or other
sequence of instructions designed for execution on a computer
system. The term "location" can be defined as a general area. The
term geographic boundary can be defined as a bounded region
specified by GPS coordinates or other mapping coordinates wherein
GPS coverage may be unavailable. The term "communication pattern"
is defined as a communication signal between one or more separate
communication units. The term "signature" is defined as a
communication pattern that is unique and repeatable. The term
"external communication system" is defined as any communication
device other than a personal area network. The term "coverage
variation limit" is defined as a range of acceptable variations in
communication patterns. The term time-series communication pattern
is defined as a communication pattern that can be recorded and
measured over time.
Embodiments of the invention concern a method and system for
authenticating a location of a device. The system can include a
tracking device having communication with one or more cellular
towers and one or more personal area networks (PANs). The PANs are
stationary devices that can be placed in locations where global
positioning system (GPS) coverage is limited or not available. The
tracking device can communicate with the one or more PANs and the
one or more cellular towers to evaluate a change in communication
signal behaviors when GPS data is unavailable. The changes in the
communication signal behavior can be compared to changes associated
with a known location of the tracking device, or more specifically,
one or more projected locations of the tracking device along a
known path. If the change in the communication patterns exceeds a
threshold, an alert can be raised, signifying that the tracking
device is in an unauthorized location. In particular, the tracking
device can monitor a series of time changes in signal strengths
between the one or more cellular towers and the one or more PANs. A
pattern of the signal strength variation can be compared to
pre-calibrated patterns associated with a monitored zone. If the
variation in the signal strength exceeds the coverage variation
limits, an alert can be raised.
As one example, the device can be attached to a user as a wearable
device for validating a location of the user. The location of the
user can be validated based on a change in communication patterns
between the tracking device and the one or more cellular towers, or
the PANs. Understandably, the tracking system can be deployed for
monitoring people or objects. For instance, the tracking device can
be attached to children for providing parental control within a
home network, or within a public area. The tracking system can also
be used for monitoring the elderly, such as Alzheimer patients,
public offenders, or employees. In one arrangement, a prescribed
zone, such as a safe zone, can be established by determining
changes in the variation of the communication signals within a
geographic region. A location of the device in the geographic
region can be validated by monitoring for unexpected changes in the
communications signals. An unexpected change is a variation in the
communication signal that is outside a coverage limit variation. In
particular, one or more communication signals can be monitored for
a transition signature, which can be used to validate a location of
the tracking device. For example, the tracking system can identify
a transition signature when the tracking device falls outside a
coverage area. Moreover, the tracking system can associate changes
in the communication signals with geographic locations for learning
new monitoring paths, that is, paths that are monitored.
Referring to FIG. 1, a tracking system 100 for validating a
location of a tracking device 160 is shown. The tracking system 100
can provide wireless connectivity over a radio frequency (RF)
communication network or a Personal Area Network (PAN).
Communication within the tracking system 100 can be established
using a wireless, copper wire, and/or fiber optic connection using
any suitable protocol (e.g., TCP/IP, HTTP, etc.). In one
arrangement, the tracking device 160 can communicate with one or
more cellular towers 110 using a standard communication protocol
such as CDMA, GSM, or iDEN. The cellular towers 110, in turn, can
connect the tracking device 160 to the Internet 120 over a packet
switched link. The Internet 120 can support application services
and service layers for providing location information to the
tracking device 160, such as monitoring services. The tracking
device 160 can also connect to other communication devices through
the Internet 120 using a wireless communication channel. The
tracking device 160 can establish connections with the server 130
on the network and with other devices on the network for exchanging
data and information. For example, the server 130 can host
application services directly, or over the Internet 120.
Applications can include monitoring applications for tracking and
validating a location of the tracking device 160.
The tracking device 160 can also connect to the Internet 120, or
the one or more cellular towers 110, over a Personal Area Network
(PAN) 104. Notably, the tracking device can establish a secure
connection to the one or more communication devices in the mobile
communication network 100. The one or more cellular towers 110 can
also be base stations. Personal Area Networks (PANs) provide
wireless access to the mobile communication environment 100 within
a local geographical area 150. In one arrangement, the PAN 104 may
be communicatively coupled with the server 130 over a wireless area
network connection. In another arrangement, the PAN 104 can
communicate directly with the one or more cellular towers 110. In a
typical PAN implementation, the physical layer can use a variety of
technologies such as 802.11b or 802.11g Wireless Local Area Network
(WLAN) technologies. The physical layer may use infrared, frequency
hopping spread spectrum in the 2.4 GHz Band, or direct sequence
spread spectrum in the 2.4 GHz Band, or any other suitable
communication technology. In particular, the tracking device 160
can send and receive data to the server 130 or other remote servers
on the mobile communication environment 100.
The tracking device 160 can be a cell-phone, a personal digital
assistant, a portable music player, an electronic map, a navigation
system or any other suitable communication device. The tracking
device 160 can communicate with the PAN 104 according to the
appropriate wireless communication standard. In one embodiment of
the present invention, the tracking device 160 is equipped with an
IEEE 802.11 compliant wireless medium access control (MAC) chipset
for communicating with the PAN 104. IEEE 802.11 specifies a
wireless local area network (WLAN) standard developed by the
Institute of Electrical and Electronic Engineering (IEEE)
committee. The standard does not generally specify technology or
implementation but provides specifications for the physical (PHY)
layer and Media Access Control (MAC) layer. The standard allows for
manufacturers of WLAN radio equipment to build interoperable
network equipment.
The tracking system 100 can monitor one or more communication
signals from the tracking device 160 to the PAN 104 and the
cellular towers 110. The tracking system 100 can include more than
one cellular tower and more than one PAN. The satellite 480 can
provide GPS readings to the tracking device and the PAN. The
tracking system 100 can validate a location of the tracking device
160 when the device is in a location where GPS location coverage is
not provided. Broadly stated, the tracking system 100 augments an
inability of a GPS system to provide location data by projecting a
location of the tracking device 160 based on previous GPS data and
validating the location based on a transitory change of the
communication signals.
Referring to FIG. 2, a tracking device 160 for generating a Radio
Frequency Time Profile (RTFP) is shown. RFTP is a time signature of
communication patterns between the tracking device 160 and one or
more separate communication units. As an example, RFTP is a time
signature of communication patterns between the tracking device
160, the one or more PANs 104, and/or the one or more cellular
towers 110 that is generated in response to changes in a location
of the tracking device 160. The tracking device 160 can include a
GPS unit 210 for receiving GPS data and identifying a location of
the tracking device, a processor 220 for processing one or more
communication signals processed by the tracking device, a first
modem 230 for communication with one or more PANs 104, and a second
modem 240 for communication with one or more cellular towers
110.
The first modem 230 and the second modem 240 can acquire a coverage
pattern from one or more cellular towers and at least one personal
area network unit. The processor 210 can then determine whether a
variation in the coverage pattern is within a monitored location.
For example, the processor captures one or more RF signals from the
first modem 230, determines a signal strength of the one or more RF
signals, and compares the coverage pattern with a coverage
variation limit of a monitored location. The first modem 230 and
second modem 240 are shown as separate modules for the purpose of
illustration only. The modulation and demodulation processes of the
first modem and second modem can be performed on the same
processor.
The processor 220 can track and store GPS readings, such as
positional data, cellular communication signals, and a PAN
coverage. For example, the processor 220 can monitor GPS data
received from the GPS unit 210, and save a history of locations to
a memory within the tracking device. Understandably, the GPS unit
210 can provide positional information when the tracking device 160
is within a GPS coverage. When GPS coverage is not available, the
tracking device 160 may not rely on GPS data to determine a
location. In this case, the tracking device 160 can rely on the
previously received GPS readings and the RTFP for validating a
location of the tracking device 160.
In particular, the processor 220 can monitor one or more
communication signals from the modem 230 to the one or more
cellular towers 110. As an example, the processor 220 can monitor a
signal strength to the one or more communication towers 110, and
save a log of the signal strengths. For example, a signal strength
can be calculated from one or more cellular communication signals
received by the modem 230. Moreover, the processor can monitor a
PAN coverage to one or more PANs. For example, a signal strength
can be calculated from one or more PAN communication signals
received by modem 240. A strength of the communication signals to
the cellular towers 110 and the PAN coverage can be calculated
periodically.
Initially, the processor 220 can determine a valid time and
location sequence of the communication signals and PAN coverage to
characterize a safe zone. For example, when the tracking device 160
has GPS coverage, the processor 220 can synchronize with the
cellular towers 110 and the PAN 104 to determine a reference time
and reference location of the PAN. The reference location can
identify a location of the PAN 104, and the reference time can
identify when the location of the PAN 104 was determined. For
example, the location of the PAN 104 can correspond to a first
location at a first time, and a second location at a second time.
In practice, it is not expected that the PAN will move during a
monitoring of the tracking device 160. In principle, the PAN 104 is
expected to be in a fixed location. However, a user attempting to
thwart monitoring activity may attempt to move the PAN 104. When
the PAN 104 is in a known location, the tracking system can
identify a location of the tracking device. However, if the PAN is
maliciously moved to a new location, the PAN may incorrectly
determine a location of the tracking device 160. Understandably,
the reference location and reference time allow the tracking system
100 to recalibrate and determine any tampering activity associated
with the tracking device. The position detector 350 (See FIG. 3)
can communicate with the satellite 480 to receive a GPS reading for
determining a location of the PAN, if GPS coverage is
available.
Notably, the PAN 104 can be positioned relative to the one or more
cellular towers 110. When GPS coverage is lost, or uncertain, the
processor 220 can compare a time signature of recent movements to
that of the reference location. The processor 220 can also evaluate
an authenticity of a location reported by the PAN 104. The PAN 104
can periodically report a location of the tracking device 160 to a
remote system, such as the server 130 in FIG. 1. For example, the
tracking system 100 may be used to track a location of person
having the tracking device 160. The server 130 can communicate with
one or more systems over the Internet for providing the monitoring
activity. For instance, one or more service providers can provide
monitoring activity of the tracking device 160 over the Internet
120 in a secure setting.
Referring to FIG. 3, components of the PAN 104 are shown. The PAN
104 can include a monitoring unit 310 for monitoring one or more
changes of a communication signal to a tracking device, a processor
320 for validating a location of the tracking device, a first modem
330 for establishing communication with one or more cellular towers
or other PANs, and a second modem 340 for establishing non-network
assisted communication with the tracking device. The monitoring
unit 310 can compare the RTFP of a tracking device 160 with one or
more communication patterns from the one or more cellular towers
110 or other PANs 104.
The PAN 104 can further include a position detector 350 for
determining a location of the PAN. Understandably, the PAN can
establish a reference point for the tracking device 160 when a
coverage is lost. Also, because the tracking device 160 may be used
to monitor dubious activity, that the PAN be located in a known
position. Accordingly, the position detector 230 in the PAN 104 can
determine whether the PAN has been tampered with; that is whether
the PAN has moved from a reference location. For example, on
power-up, or at a time when the unit is authenticated, a location
of the PAN 104 can be determined via GPS readings, or through a
servicing arrangement, wherein the physical position is hard-coded
in the device.
Referring to FIG. 4, an exemplary tracking device scenario 400 is
illustrated. In particular, the scenario 400 illustrates coverage
areas for validating a tracking device 160 when GPS coverage is
unavailable. The operation of the tracking device 160 is not
limited to the physical arrangement and placement of the devices
and components shown in FIG. 4. Various arrangements of the devices
for validating a coverage of the tracking device 160 are herein
contemplated. In the foregoing, a brief description of the coverage
areas for the tracking device 160 is presented. Notably, the
description of the tracking device 160 is discussed in relation to
a coverage of one or more cellular towers and a coverage of one or
more PANS for validating a location of the tracking device 160,
although the invention is not so limited.
In scenario 400, the home 410 in the foreground can be considered a
legitimate location. In contrast, the home 420 in the background
can be considered an unauthorized location. A legitimate location
corresponds to an allowed location of the tracking device 160. For
example, the tracking device 160 may be attached to a user that is
required to stay within an authorized location, such as the home
410. Understandably, one objective of the tracking system is to
determine, within a measure of confidence, if the user has left the
authorized location. Another objective is to validate a location of
the user when GPS coverage is unavailable based on previous GPS
readings and the RFTP. Initially, the tracking device 160 can
establish an RFTP that corresponds to the authorized location of
the home 410. For example, the RFTP can be synchronized (e.g.
calibrated) with the PAN 104 for establishing the authorized
location and the RFTP.
Also, as a result of the synchronization (e.g. calibration), the
tracking device 160 knows that location B1 (452) corresponds to
intermittent GPS readings when the tracking device is at location
B1 (452). That is, the tracking device 160 has a priori knowledge
of coverage conditions due to the synchronization of the tracking
device at a reference location, such as the home 410, based on the
RFTP. At location B1 (452), the tracking device 160 will also be
visible to the PAN 104 within the home 410. At location B1 (452),
the tracking device 160 will also have the cellular tower X (110)
as its prime cell and cellular tower Y (112) as a distant signal.
Accordingly, RFTP can be evaluated for validating a location of the
tracking device 160 within location B1 because cellular coverage is
available.
Location A (450) has GPS coverage from the satellite 480, as well
as visibility to cellular towers X (110), Y (112), and Z (114).
Accordingly, the cellular towers can validate a location of the
tracking device at location A (450) based on the RFTP. As
previously noted, Location B1 (452) is where GPS coverage is
becoming intermittent or non-existent. Accordingly, the tracking
device 160 still has cellular coverage at location B1, though, is
entering coverage of the home PAN 104. The location of the tracking
device 160 at location B1 can thus be validated based on the RFTP
which is available to the PAN 104. The location of the tracking
device 160 can also be determined by the cellular towers X (110)
and Y (112) at location B1.
Location C1 (454) has no GPS visibility from the satellite 480,
though it does have cellular coverage to cellular tower X (110) and
Y (112). Accordingly, a tracking device 160 within location C1
(454) can be validated by a home computer 130 or set-top box
connected to the PAN 104. That is, the PAN 104 can validate a
location of the tracking device 160 as an authorized location based
on the RFTP. Location C2 (452) has no GPS or cellular coverage,
though a tracking device 160 at location C2 (452) can be detected
by the home PAN 104. That is, an RFTCP of the tracking device 160
at location C2 (452) can be validated because the PAN 104 can
communicate with the tracking device 160.
In contrast, Locations B2 (458) and C3 (460) are unauthorized
locations. At location C3 (460) the tracking device may not have
GPS coverage or cellular coverage. Accordingly, when the tracking
device 160 is in either location B2 (458) or C3 (460), the PAN
profile can be very similar to the PAN profile of the foreground
home 410. That is, from the perspective of the tracking device 160,
the signals received from PAN 106 at location B2 are similar to the
signals received from PAN 104 at location B1. However, the RFTP
reveals that the tracking device 160 lost GPS connectivity from the
satellite 480 under a different latitude and longitude. Moreover,
the cellular coverage at location B2 reveals that the prime
cellular tower for tracking device 160 at location B2 (458) is X,
which is different from the RFTP of the tracking device 160 at
location B1 (452). Notably, the coverage conditions have changed in
accordance with a movement of the tracking device 160 though GPS
coverage is unavailable. The tracking system can consider this an
alert situation.
Referring to FIG. 5, a method 500 for generating an RFTP is shown.
The method 500 can be practiced with more or less that than the
number of steps shown. To describe the method 500, reference will
be made to FIGS. 4, 6, and 7 although it is understood that the
method 500 can be implemented in any other suitable device or
system using other suitable components. Moreover, the method 500 is
not limited to the order in which the steps are listed in the
method 500. In addition, the method 500 can contain a greater or a
fewer number of steps than those shown in FIG. 5.
At step 502, the method can start. At method 502 GPS readings
received by a tracking device can be tracked and stored for
identifying one or more locations of the tracking device. For
example, referring back to FIG. 4, one or more sets of GPS readings
can be taken from the satellite 480 by the tracking device 160. The
tracking device 160 can track and store one or more network
readings including GPS data, cellular signals, RF signal strengths,
and PAN coverage, for creating the RFTP. The GPS readings can be
stored in a history buffer, such as a data store or memory.
Notably, the tracking device 160 takes the GPS readings when GPS
coverage is available. The tracking device 160 can also determine a
time and location sequence from one or more network readings for
characterizing a safe zone.
At step 506, a set of time-series communication patterns can be
captured between the tracking device and one or more Personal Area
Networks (PANs). For example, referring to FIG. 4, the tracking
device 160 can record changes in PAN signals between the tracking
device 160 and the PAN 104 and/or PAN 106. The set of time-series
communication patterns between the tracking device 160 and the PANs
can be determined in a manner similar to that shown in FIG. 6.
Understandably, the PAN signals are received from the PANs instead
of the cellular towers for determining the second set of
time-series communication patterns.
At another step (not shown), a set of time-series communication
patterns can be captured between the tracking device and one or
more cellular towers. For example, referring to FIG. 4, the
tracking device 160 can record changes in a RF communication
signals sent between the tracking device 160 and the one or more
cellular towers X (112), Y (114), and Z (110). For example,
referring to FIG. 6, a first set of time-series communication
patterns between the tracking device 160 and the cellular towers is
shown. For example, a first time series communication pattern 620
can be recorded from cellular tower X 110. A second time series
communication pattern 622 can be recorded from cellular tower Y
112. And, a third time series communication pattern 624 can be
recorded from cellular tower Z 114. The time series communication
pattern can be network readings including GPS data, cellular
signals, or RF signal strengths.
At step 508 a pre-calibrated Radio Frequency Time Profile (RTFP)
can be generated from the first set of time-series communication
patterns and the second set of time-series communication patterns.
As an example, the RFTP is a time signature of communication
patterns between the tracking device 160, the PANs 104 and 106, and
the one or more cellular towers (110, 112, 114) that is generated
in response to changes in a location of the tracking device 160.
For example, referring to FIG. 7, an RFTP trace for the
communication signals recorded between the tracking device 160 and
the cellular tower X (110) is shown. The RFTP trace can be captured
over a time interval t=0 (640) to t=N (650). Notably, the RFTP
trace can include a coverage variance 720 at each time step in the
time interval. For example, multiple readings between the tracking
device 160 and the cellular tower X (110) can be recorded at a
multiple time steps. A variance of the recordings can be determined
for identifying a coverage variance. Upon future RFTP readings,
coverage variance will determine whether a received communication
signal is validated based on the coverage variance of the reference
RFTP. For example, an average of a time series communication
signals should be expected to fall within the coverage variance
720, if the time series communication signals are captured along a
pre-calibrated path. If the average does not fall within the
coverage variance, a location of the tracking device 160 based on
the RFTP trace cannot be validated. Understandably, the RFTP trace
establishes a reference for identifying bounded changes in a
communication signal pattern wherein the bounded changes occur
along a physical pre-calibrated path. Notably, the RFTP consists of
RFTP traces from one or more cellular towers and one or more
PANs.
The steps 502, 506, and 508 are performed during a calibration
period, or synchronization period, when the locations of the PANs
are known and verified. Upon completion of the calibration period,
the tracking device 160 can monitor changes in one or more sets of
time-series communication patterns and compare the changes to the
RFTP 700 acquired during the calibration period. Notably, the
tracking device 160 can identify coverage transitions based on the
RFTP acquired during the calibration period. At step 509, the
method 500 can end. In particular, the steps 502, 506, and 508 of
the calibration period can include characterizing a safe zone, such
as an authorized location, through drive testing. Drive testing
includes, taking the tracking along a path that may be traveled by
a user wearing, or holding, the tracking device 160 for recording
the time-series communication patterns to generate the RFTP.
For example, referring to FIG. 4, a common path, such as a street
between the close home 410 and the far home 420 can be drive tested
to generate a reference RFTP. That is, the tracking device 160 can
be driven in a car along the street between the close home 410 and
the far home 420 for characterizing one path. Multiple paths can be
drive tested for creating the reference RFTP. The reference RFTP
captures a time profile describing how readings of the
communication signals from all network elements vary along a
reported path. Likely paths are pre-calibrated via "drive testing"
or "walk testing", where a tester walks a certain path and RF
fingerprint information is recorded and uploaded to a database.
That is, one or more paths are characterized by physically moving
the device along the path and recording changes in communication
signal behavior. The changes in the communication signal behavior
can correspond to transition signatures which identify one or more
locations of the tracking device 160. Moreover, a time and location
sequence of the tracking device can be determined from changes in
the network readings for characterizing a safe zone.
Referring to FIG. 8, a method 800 for determining an authorized
location is shown. The method 800 can be practiced with more or
less than the number of steps shown. To describe the method 800,
reference will be made to FIG. 4 although it is understood that the
method 800 can be implemented in any other suitable device or
system using other suitable components. Moreover, the method 800 is
not limited to the order in which the steps are listed in the
method 800. In addition, the method 800 can contain a greater or a
fewer number of steps than those shown in FIG. 8.
At step 801, the method can start. The method 800 can start in a
state where a pre-calibrated (e.g. reference) RFTP has been
generated for one or more paths of an authorized location, and
where GPS coverage has recently become unavailable. At step 802, a
path of the tracking device can be projected based on a present
RFTP and one or more last received GPS locations. For example,
referring to FIG. 4, the tracking device 160 at location C2 (452)
may have previously received GPS data reporting an immediate
location of the tracking device. For example, the last received GPS
reading was at location B1 (452), the last cellular coverage was
received by cellular tower X (110) at location Cl, and the current
RFTP shows the tracking device 160 is in proximity of the PAN 104.
The PAN 104 can project a path of the tracking device based on a
history of the GPS readings, and the present RFTP. Accordingly, the
path can be predicted as B1->C1.
At step 804, a location of the tracking device can be predicted
based on the path. For example, referring to FIG. 4, the tracking
device 160 at location C1 does not have coverage to GPS readings by
the satellite 480. Accordingly, the PAN 104 can only rely on
previous GPS readings and the RFTP. The RFTP can identify changes
in communication signal readings between the tracking device 160,
the PAN 104, and the cellular towers X (110) and Y (112) that
provide reception to the tracking device 160. For example, the last
received GPS reading was at location B1 (452), the last cellular
coverage was received by cellular tower X (110) at location C1, and
the current RFTP shows the tracking device 160 is in proximity of
the PAN 104. Accordingly, the path can be predicted as B1->C1
with a predicted location of C2.
At step 806, the location of the tracking device can be validated
within a monitored location in view of the pre-calibrated RFTP. For
example, referring to FIG. 4, the tracking device 160 at location
C2 (452) can be validated if the RFTP readings are within a
coverage variance. For example, referring to FIG. 7, if the RFTP
traces fall within the coverage variation limit 720, the location
of the tracking device 160 can be validated.
At step 808, an alert can be raised if the path deviates outside a
coverage variation limit of the pre-calibrated path. For example,
referring to FIG. 4, if the tracking device 160 is at location C3
(460) an alert can be raised. At location C3 (460), the RFTP will
not fall within coverage variation limits 720 associated with the
safe zone of home 410. Moreover, a history of the communication
pattern transitions when compared to the RFTP will reveal that the
device has moved out of the safe zone of the home 410. That is, a
time signature of recent movement when compared to the RFTP
coverage variance indicates that movement outside the safe zone has
occurred, and which corresponds to an unauthorized location. In
particular, the tracking device 160 can validate a location when a
history of the communication signal activity falls within a
coverage limit variation, but cannot validate a location when the
communication signal activity is greater than the coverage limit
variation.
At step 810, a determination can be made as to whether the alert is
valid. If the alert is valid, the coverage variation limit can be
enforced. If the alert is invalid, a coverage variation limit can
be extended for reducing a false alarm rate. The tracking device
can update the RFTP based on one or more false alarms. In summary,
the method 800 predicts a location of the tracking device along a
path when GPS data for reporting a location of the tracking device
is unavailable, determines whether the location is within a region
of a last received GPS reading, and raises an alert if the location
is outside a coverage variation limit of a pre-calibrated path. The
tracking device 160 can learn changes in the RFTP based on an alarm
rate, for reducing false alarm rates.
Referring to FIG. 9, a method 900 for validating a location of a
tracking device based on monitoring signal strengths is shown. The
method 900 can be practiced with more or less than the number of
steps shown. To describe the method 900, reference will be made to
FIGS. 4, 7, and 10 although it is understood that the method 900
can be implemented in any other suitable device or system using
other suitable components. Moreover, the method 900 is not limited
to the order in which the steps are listed in the method 900. In
addition, the method 900 can contain a greater or a fewer number of
steps than those shown in FIG. 9.
At step 901, the method can start. At step 902, a set of signal
strengths to one or more cellular towers can be monitored. For
example, referring to FIG. 10, a set of signal strengths between
the tracking device 160 and one or more cellular towers is shown.
The signal strengths can be identified as a magnitude, a peak
signal level, or an average signal level. A signal strength
variation can also be associated with the signal strengths. For
example, the tracking device 160 can reveal a signal strength
variation .delta.x 630 with cellular tower X (110), a signal
strength variation .delta.y 632 with cellular tower Y (112), and a
signal strength variation .delta.z 634 with cellular tower Z (114).
Notably, the signal strengths may vary depending on the cellular
tower power and the distance from the cellular tower to the
tracking device 160.
At step 904, a set of signal strengths to one or more personal area
networks (PANs) can be monitored. For example, the tracking device
160 can reveal a signal strength variation .delta.p1 730 with PAN
104, and a signal strength variation .delta.p2 732 with PAN 106.
Notably, the signal strengths may vary depending on the PAN power
and the distance from the PAN to the tracking device 160. It should
also be noted that the tracking device 160 and the PANs can
communicate over a non-network assisted communication protocol
including at least one from the group comprising: BlueTooth,
ZigBee, IEEE 802.11, and two-way radio.
At step 906, a Radio Frequency Time Profile (RTFP) can be generated
from the set of signal strengths, wherein the signal strengths
change over time. The RFTP is a time series of the signal strengths
between the tracking device and the one or more PANs resulting from
a change in location of the tracking device. Briefly referring back
to FIG. 7, the RFTP for the signal strengths can be calculated in a
manner analogous to the RFTP 720 of FIG. 7. Notably, a coverage
variation for the signal strength can be determined for each RFTP
trace.
At step 908, the Radio Frequency Time Profile can be compared to
coverage variation limits of one or more pre-calibrated paths.
Notably, the RFTP includes a first set of signal strength
indicators measured between the tracking device and the one or more
cellular towers, and a second set of signal strength indicators
measured between the tracking device and the one or more PANs.
Referring to FIG. 4, the tracking device 160 monitors a first
variation in the first set of signal strength indicators and a
second variation in the second set of signal strengths over a time
window for determining whether the variations are within a coverage
variation limit of a monitored location.
At step 910, an alert can be signaled if the set of signal
strengths are not within the coverage variation limit of the one or
more pre-calibrated paths. For example, referring to FIG. 4, if the
tracking device 160 moves to location C3 (460), the signal strength
indicators to the PAN 104 and the signal strength indicators to the
PAN 106 will change in a manner that is not consistent with signal
strength coverage variation limits of the RFTP.
Referring to FIG. 12, a method 930 for creating pre-calibrated
coverage variation patterns during a pre-calibration period is
shown. The method 930 can be practiced with more or less than the
number of steps shown. To describe the method 930, reference will
be made to FIGS. 10 and 11 although it is understood that the
method 900 can be implemented in any other suitable device or
system using other suitable components. Moreover, the method 900 is
not limited to the order in which the steps are listed in the
method 900. In addition, the method 930 can contain a greater or a
fewer number of steps than those shown in FIG. 10.
At step 931, the method 930 can start. At step 932, one or more
communication patterns can be captured along a pre-specified path
of a monitored location. At step 933, variations in the one or more
communication patterns can be identified along the pre-specified
path. At step 934, a coverage variation limit can be determined for
the variations along the pre-specified path. At step 935, a
geographic boundary can be established for the pre-specified path.
Upon creation of the pre-calibrated coverage variation patterns,
signal strengths in the RFTP for current locations can be compared
to the coverage variation limit for determining whether a location
of the tracking device is within the geographic boundary.
Where applicable, the present embodiments of the invention can be
realized in hardware, software or a combination of hardware and
software. Any kind of computer system or other apparatus adapted
for carrying out the methods described herein are suitable. A
typical combination of hardware and software can be a mobile
communications device with a computer program that, when being
loaded and executed, can control the mobile communications device
such that it carries out the methods described herein. Portions of
the present method and system may also be embedded in a computer
program product, which comprises all the features enabling the
implementation of the methods described herein and which when
loaded in a computer system, is able to carry out these
methods.
While the preferred embodiments of the invention have been
illustrated and described, it will be clear that the embodiments of
the invention are not so limited. Numerous modifications, changes,
variations, substitutions and equivalents will occur to those
skilled in the art without departing from the spirit and scope of
the present embodiments of the invention as defined by the appended
claims.
* * * * *
References